This invention relates to an energy efficient process and apparatus for desalinizing water, and more particularly to a desalinization system which uses a temperature differential created within the context of the weather environment in which the apparatus is located to furnish the heat of vaporization required to boil salt water and to dissipate heat of condensation.
There are many known methods of desalinizing water based on distillation. Considerable effort has been expended attempting to design a system capable of producing fresh water at a cost low enough to service a large population or agricultural area. In general, the approach has been to conserve the heat given up when water vapor condenses to vaporize additional quantities of water, thus reducing the total amount of heat used per unit mass of fresh water produced.
In designing a desalinization system, there are essentially two areas of cost which must be considered: initial capital outlay; and the ongoing operational cost which includes the price of the energy consumed and the price of maintenance. In areas where local natural supplies of fresh water are low, the capital costs of constructing a large desalinization plant will often be competitive with the costs of a pipeline. However, operational expenses are another matter, and as the cost of energy increases, the possibility that desalinization water can compete with piped sources of fresh water has become more remote. Nevertheless, there are areas of the world which could be developed to support sizeable populations if provided with fresh water, yet many of these are located such that no significant possibility exists for servicing the land with natural fresh water.
Almost by definition, these areas are hot and dry, and accordingly are characterized by low humidity and days of uninterrupted direct solar exposure. Under these conditions, it is now possible to produce a sizeable temperature differential without consuming energy generated from fossil or nuclear fuels. Rather, "hot" and "cold" thermal sinks may be produced by taking advantage of ambient conditions.